(1) Field of the Invention
This invention is related to vertical shaft impact rock crushers. Rock crusher operators have ordinary skill in this art.
(2) Description of the Related Art
Impact rock crushers have been known for over thirty years. See Miller U.S. Pat. No. 3,174,698 and Bridgewater U.S. Pat. No. 3,174,697. However before this invention the crushers had two major problems. The first was vibration. By adding a large mass of rocks to be crushed the rocks would flow into a impeller rotating at high speed in uneven amounts. With the changing flow of the rocks within the impeller the impeller would almost always be imbalanced and vibrate accordingly.
Another problem was the abrasion. The rocks moved over metal parts within the rotors or impellers and their movement would quickly abrade the parts. Also, larger rocks impacting the impellers required them to be of rather heavy material.
The abrasion problem was at least in part alleviated by forming rock packs or packed material in pockets to provide the surface that the rocks abraded. Such structure is shown for example in Bridgewater U.S. Pat. No. 3,174,697 as well as Canada 5,145,118, Bartley 4,921,173, Terrenzio 4,513,919, Szalanski 4,560,113 and Watajima 4,844,354. The Szalanski rock pack of FIG. 5 is of particular interest.
The maintenance costs of a rock crushers is a considerable amount. Before this invention, the cost of replacing worn parts of the rock crusher could be as high as the 10% of the value of the rock crushed.
It is has been known for over a hundred years that a fluid or fluidlike material could be placed within the rings on spinning structure such as Withee 229,787. However, generally these have been used only upon structures which do not have the magnitude of unbalance such as the rotors of rock crushers. For example, Withee was concerned with balancing a millstone which would have basically been symmetrical in any event. He suggested that the fluidlike material could be shot, sand or water.